# 7. Annotator
Sample implementation of annotator highlighting resolved and unresolved Simple language properties in Java strings.
**Reference**: [](syntax_highlighting_and_error_highlighting.md#annotator)
**Code**: [`SimpleAnnotator`](%gh-sdk-samples-master%/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java)
**Testing**: [](annotator_test.md)
An `Annotator` helps highlight and annotate any code based on specific rules.
This section adds annotation functionality to support the Simple Language in the context of Java code.
## Required Project Configuration Changes
Classes defined in this step of the tutorial depend on `com.intellij.psi.PsiLiteralExpression` (the PSI representation for String literals in Java code) at runtime.
A dependency on the [Java plugin](idea.md#java) must be [declared explicitly](plugin_dependencies.md).
First, add a dependency on the Java plugin in the Gradle build script:
```kotlin
dependencies {
intellijPlatform {
// ...
bundledPlugin("com.intellij.java")
}
}
```
See [build.gradle.kts](%gh-sdk-samples-master%/simple_language_plugin/build.gradle.kts) for the reference.
Then, declare the dependency in [plugin.xml](plugin_configuration_file.md) (use code insight)
```xml
com.intellij.java
```
## Define an Annotator
The [`SimpleAnnotator`](%gh-sdk-samples-master%/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java) subclasses [`Annotator`](%gh-ic%/platform/analysis-api/src/com/intellij/lang/annotation/Annotator.java).
Consider a literal string that starts with "simple:" as a prefix of a Simple Language key.
It isn't part of the Simple Language, but it is a useful convention for detecting Simple Language keys embedded as string literals in other languages, like Java.
Annotate the `simple:key` literal expression and differentiate between a well-formed vs. an unresolved property.
```java
```
{src="simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java" include-symbol="SimpleAnnotator"}
> If the above code is copied at this stage of the tutorial, then remove the line below the comment _** Tutorial step 19. …_ as
> `SimpleCreatePropertyQuickFix` is not defined until [later](quick_fix.md) in the tutorial.
>
{title="SimpleCreatePropertyQuickFix"}
## Register the Annotator
Using the in the plugin configuration file, register the Simple Language annotator class for `JAVA` language:
```xml
```
## Run the Project
Run the plugin by using the Gradle [`runIde`](creating_plugin_project.md#running-a-plugin-with-the-runide-gradle-task) task.
As a test, define the following Java file containing a Simple Language `prefix:value` pair:
```java
public class Test {
public static void main(String[] args) {
System.out.println("simple:website");
}
}
```
Open this Java file in an IDE Development Instance running the `simple_language_plugin` to check if the IDE resolves a property:
{width="800"}
If the property is an undefined name, the annotator flags the code with an error.
{width="800"}
Try changing the Simple Language [color settings](syntax_highlighter_and_color_settings_page.md#run-the-project) to differentiate the annotation from the default language color settings.